SWith the development of economy and society, the land resources occupied by traffic projects are becoming more and more precious. In order to make full use of the land used by expressways, most places require expressways to be built according to the mode of viaduct, and local places use the space under the bridge to build ground roads, Combined with the phase II ground road project of Ningbo section of G92 Hangzhou Ningbo Expressway double line, this paper fully studies the safety impact of subgrade construction under the high-speed bridge on the existing expressway bridge, especially for the section where the roadside Auxiliary Pier is set for the high-speed interchange, the uneven load is formed on both sides of the Auxiliary Pier during the subgrade filling of the ground road, resulting in horizontal pushing on the auxiliary pier, There are certain potential safety hazards for Auxiliary Pier Pile Foundation. Through the full analysis of the impact of subgrade filling on bridge pile foundation, three treatment schemes are put forward, which are compared and analyzed from the aspects of investment, land use, bearing platform and pier column displacement, combined with the actual situation of the project, the recommended scheme is put forward, and the specific requirements for monitoring during construction are put forward. This study can provide useful technical reference for the subgrade filling construction scheme of elevated combined with ground road in the future.